It is known in the art that by subjecting non-ferrous metal pieces to a high density, rapidly changing, magnetic flux field, eddy currents are induced in the pieces. The eddy currents produce a repulsive magnetic force in the pieces that is generally proportional to the resistance of metal which comprise the pieces. This repulsive force can cause the respective pieces, when passed through such flux, to be forced away from the field in different trajectories, depending upon the types of metal. Thus, by subjecting substantially similar-size pieces to such a magnetic flux field, their different trajectories permit the pieces to be collected in different containers.
When moving different pieces, of approximately the same size, or different metals through such a rapidly changing, high-density, magnetic flux field, the pieces made of electrically conductive material tend to fly freely a substantial distance from the field. Plastic will be unaffected by the field. Thus, electrically conductive material can be separated from non-conductive materials to produce the required magnetic field, a magnetic rotor may be utilized.